There is a need for improved antiparasitic agents for use with animals, and in particular there is a need for improved insecticides and acaricides. Furthermore there is a need for improved topical and oral products with convenient administration and which contain one or more of such antiparasitic agents which can be used to effectively treat ectoparasites, such as insects (e.g., fleas, lice, and flies) and acarids (e.g., mites and ticks). Such products would be particularly useful for the treatment of animals including: birds (e.g., chickens and turkeys), fish, companion animals (e.g., cats, dogs, llamas, and horses), and livestock (e.g., cattle, bison, swine, sheep, deer, elk, and goats). The compounds of the instant invention would also be particularly useful as an insecticide for plants.
The compounds currently available for insecticidal and acaricidal treatment of animals do not always demonstrate good activity, good speed of action, or a long duration of action. Most treatments contain hazardous chemicals that can have serious consequences, including neurotoxicity and lethality from accidental ingestion. Persons applying these agents are generally advised to limit their exposure. Pet collars and tags have been utilized to overcome some problems, but these are susceptible to chewing, ingestion, and subsequent toxicological affects to the animal. Thus, current treatments achieve varying degrees of success which depend partly on toxicity, method of administration, and efficacy. Currently, some agents are actually becoming ineffective due to parasitic resistance.
Isoxazoline derivatives have been disclosed in the art as having insecticidal and acaricidal activity. For example, WO2007/105814, WO2008/122375, and WO2009/035004 recite certain alkylene linked amides. WO2010/032437 discloses that the benzyl amide can be moved to the position ortho to the isoxazoline. Further, WO2007/075459 discloses phenyl isoxazolines substituted with 5- to 6-membered heterocycles, and WO2010/084067 and WO2010/025998 disclose phenyl isoxazolines substituted with 10- to 11-membered fused aryl and heteroaryls. Chiral processes for manufacturing isoxazolines have been reported in WO2011/104089 and WO2009/063910. Some spiro-azetidine isobenzofuran derivatives for the treatment of diabetes and hyperlipidemia were described in WO2008/096746. Spirocyclic azetidines were published in WO2012/017359. In addition, spiroisoxazolines were recently filed in PCT/IB2012/050842. However, none of these citations exemplify pyridyl spirocyclic substituted isoxazolines, or processes of manufacturing the same, nor does the prior art indicate that such compounds would be useful against a spectrum of parasitic species relevant to companion animals, livestock or fowl against the range of parasitic morphological lifecycle stages.
Despite the availability of effective, broad spectrum antiparasitic agents, there remains a need for a safer, convenient, efficacious, and environmentally friendly product that will overcome the ever-present threat of resistance development.
The present invention overcomes one or more of the various disadvantages of, or improves upon, the properties of existing compounds. In particular the present invention develops new spirocyclic isoxazoline substituted azetidine compounds which demonstrate such properties.